Jump to content

UPDATE: you're up to 100 mph, would you kill the engine, or shift into neutral?


LarryC

Recommended Posts

  • Replies 100
  • Created
  • Last Reply

Top Posters In This Topic

I had a Ford Bronco when I was in college. I was driving on campus while class was letting out with people walking everywhere.

My accellerator got stuck under the floor mat and floored the engine. I stood on the brake but it was not enough to stop the truck. I put it in neutral, the engine reved like crazy and I turned it off. Needless to say, the spinning back tires, the crazy engine sounds etc, created quite a site. People were like what is wrong with you?

Scared me to death, I could have very very easily ran over several people walking across the street. I had the truck towed to dealer. The throttle pedal was looked at and found to be fine. Then the tech and I noticed the mat flip up and over the pedal. Bingo.

Got rid of those mats, and to this day I very regularly look to see where my floor mats are on the floor of my truck.

Paul

Link to comment
Share on other sites

Back in high school a girl named Chrystal owned about '65 Ford Fairlane four door. One day I'm just starting to walk out in the school parking lot, and see a white car flying like it hit a ramp, land and smash the back of another car.

(The lot had long island strips breaking it down into four sections. The island strips were about four feet wide, and had streetlights mounted along the length of them. The islands were 12" tall)

I dunno if she got a floormat hung up on the gas pedal, or just stomped on it for no apparent reason......but she hit the island from one side, shot the car straight up about 75 degrees, and parked the front end of her car on top of the deck lid of a '69 Nova on the other side of the island. Crushed the trunk, blew out the back window, did some rather extensive damage.

The guy that owned the car was poor struggling gearhead, that loved that ol' ragged Nova. He was so p*ssed...........

Link to comment
Share on other sites

Twisted, when a rev limiter kicks in it actually lowers the revs below the peak that it kicks in. For the sake of this case I get the impression no limiter kicks in, because if it did a driver would gain a sense of what to do.

Oldtimer,

I agree, something fishy about the whole story, just like all the brake failures when there is an accident, but no apparent problem afterwards, or all the females that get pregnant "but I was on the pill" when the pill is 99.9% clinically proven effective. The numbers don't add up, or like the photo shopped picture of that car and train.....

As for the electronic fuel injection, I'm not a mechanic, just a gear head. I've never worked on electronic fuel injection, but I have worked on mechanical settups. [;)]

Roger

Link to comment
Share on other sites

Most modern cars have speed limiters, not rev limiters. They get up to a certain speed (172km/hr/107mph with mid-'90s Chevy Luminas, 188km/hr/117mph with some Dodge products, 255km/hr/158mph with some Mercedes cars, for just a few examples) and don't go any faster. Some do it smoothly, others get kind of jumpy when they hit their limited speed.

One benefit to the car manufacturers is that they can fit tires with lower speed ratings, like S or T, which are cheaper. That really adds up when you're buying hundreds of thousands of tires to fit to the cars coming out of those factories.

Link to comment
Share on other sites

One benefit to the car manufacturers is that they can fit tires with lower speed ratings, like S or T, which are cheaper. That really adds up when you're buying hundreds of thousands of tires to fit to the cars coming out of those factories.

Interesting. Some formerly faster models like Mercedes E or Lexus models are now limited to 135 mph, which just happens to be the max for H rated tires. H's are more comfortable than 150 mph V-rated's IMO.

Some places like tirerack.com won't sell H-rated tires for cars with advertised top speeds that warrant a V-rated tire, even if the customer declares he/she has no intention of driving that fast. I'm glad, because V-rated tires are costlier, noisier, and have a harsher ride.

Link to comment
Share on other sites

H's are more comfortable than 150 mph V-rated's IMO.

Some places like tirerack.com won't sell H-rated tires for cars with advertised top speeds that warrant a V-rated tire, even if the customer declares he/she has no intention of driving that fast.


I beg to differ about that. After the OEM Michelins on my Dodge Grand Caravan wore out, I planned to get a set of H-rated tires, but my friendly tire dealer (Cheap Thrills, in Milton, Ontario), suggested the Bridgestone Potenza 730, a V-rated tire, since he knows I'm an enthusiastic driver and would appreciate the improved handling. I didn't need the higher speed rating with the low limited speed of the mini-van, but it seems that the stronger carcass of the higher-rated tires means they have stiffer sidewalls, which results in a lower slip angle, or in layman's terms, a more immediate response to steering inputs.

I was prepared for a rougher ride, but was surprised to find that it was just as smooth as with the Michelins, but the traction and handling was much better. Even passengers noticed and commented on the sportier feel of the vehicle.

Tires have a wet traction rating marked on the side, usually A or B, but the 730s have an AA rating, and it's easy to notice how well they grip when driving in the rain. When these wear out, I'll be buying another set of V-rated Bridgestones.

As for Tire Rack's policy, they are completely correct. If they were to sell tires that didn't meet the car manufacturers' specs, it could be dangerous and could leave them open to legal action in the even of a tire-related incident.
Link to comment
Share on other sites

Twisted, when a rev limiter kicks in it actually lowers the revs below the peak that it kicks in. For the sake of this case I get the impression no limiter kicks in, because if it did a driver would gain a sense of what to do.

Oldtimer,

I agree, something fishy about the whole story, just like all the brake failures when there is an accident, but no apparent problem afterwards, or all the females that get pregnant "but I was on the pill" when the pill is 99.9% clinically proven effective. The numbers don't add up, or like the photo shopped picture of that car and train.....

As for the electronic fuel injection, I'm not a mechanic, just a gear head. I've never worked on electronic fuel injection, but I have worked on mechanical settups. Wink

Roger

I've run up the revs to get the limiter to kick in a few times. It's a real buzz kill. The 71 alfa doesn't have one so one is only limited by their intelligence for potentially blowing the engine. Haven't hit the limiter for the 91 alfa either, come to think of it.

Link to comment
Share on other sites

My volvo had the throttle cable get stuck one time on the way to the store in Orlando.

I just popped it into neutral and cut the engine and coasted into a parking lot.

I was used to no power steering because I took the pump out to make room for the fatty mandrel bent intercooler piping [6]

It didn't have a speed limiter(that I could find).

I think it had a rev limiter in the stock ECU that I think was set to 6500 rpm and with the auto tranny I never got that high.

130+mph in overdrive was only 5200rpm.

Did none of these people try and use the emergency brake?

Link to comment
Share on other sites

All motorcycles have kill switches but no car does? I wonder why,it's good for bikes and not for cars? I have had stuck throttles, I just turned off the engine, I guess I've been wrong all this time? You loose power assist after a short time but you can still brake and turn. My car has 400 hp, if the gas sticks you want to turn it off quick before you gain too much speed. You are not going to be able to select neutral very well when you are pinned in the seat and gaining speed fast, plus you'll need both hands to steer when the power steering fades.

Thanx, Russ

Speaking from a standpoint of someone with alot of miles behind 1,400 HP, I have my doubts as to why anybody who would think it would be a panic descission behind 400 HP, should even have a drivers liscense!!

Having said the pevious, I will state the obvious; Almost all new cars come standard with a rev limiter!! Puting it into neutral and applying the brakes won't hurt the engine a bit!!!!

Putting the engine in a lower gear at too many RPMs could over rev and blow the engine!!

Turning the engine off with a stuck throttle with fuel injection could possibly hydraulic the engine!!

Doesn't take alot of thought here, just some basic understanding of how an engine works!!

Roger

Hydrolock perhaps?

Pretty much impossible with efi.

Cutting the ignition is going to cut voltage to the injectors and injectors without power are stuck closed not open.

I also have my doubts as to the amount of fuel being dumped to be enough to lock the engine up but the numbers would vary by car and engine depending on Air Fuel Ratio at said RPM and compression ratio of the engine which would determine how much room inside combustion chamber could be filled with fuel before exhibiting hydraulic pressures against the piston on the combustion stroke.

-Josh

Link to comment
Share on other sites

Westie, I've never driven a car with a speed limiter but many with a rev limiter.


Years ago, when I was driving rental Luminas around Toronto for a while, bouncing them off the speed limiter in freeway traffic happened almost every day. However, traffic speeds in Ontario may be lower these days, since there's now a charge called "stunt driving", which can be applied to anyone caught going more than 50km/hr (31mph) over the posted limit. Conviction can result in a $10,000 fine and impoundment of the vehicle.

With automatics, the tranny selects the shift point, so I don't know if they have rev limiters. I never bothered to floor it in neutral and see what happened, which is likely the only way the rev limiter would come into play.
Link to comment
Share on other sites

Drivers don't drive automatics. The day I drive an automatic is the day I am physically unable to drive a standard, and then there might be a case for not driving at all.


I used to think that way (my first car was a stick-shift Corvette), but when I started driving ex-police cruisers, I found that it was easy to shift with the gas pedal, especially with the electronically controlled GM 700R4 4-speed automatic. Those cars, the injected Caprices at least, have an adaptive engine management system that responds to the driving style. If you usually drive it fast, it becomes fast. Mechanics who test-drove it often remarked that it seemed unusually responsive.

The police-version transmissions seem to be programmed to shift at higher revs and to downshift more readily than civilian versions, so you actually could control the shifting with the gas pedal. You didn't have the fun of double-clutching on downshifts, but it always seemed to be in the right gear at the right time. I still miss my 5.7L police Caprice.
Link to comment
Share on other sites

Drivers don't drive automatics. The day I drive an automatic is the day I am physically unable to drive a standard, and then there might be a case for not driving at all.

I'm not a driver but I am a racer. I can row a manual trans without any problems but my race cars are automatics.

Thanx, Russ

Link to comment
Share on other sites

The early 700-R4's in the standard Corvettes would shift at (governor controlled) 5700 rpm at full throttle in first gear in drive position. The 700 R4 transmission went through several very extensive revisions to keep it together, one in 1985 and the other in 1987. I spent $850.00 upgrading a 700-R4 to 1985 standards not including the rebuild kit and GM auto trans repair tools. The guy that invented this tranny has to be in the loony bin. Twenty-one check balls and you better get them in the right spot. And that's the easy part. The hardest part was that dumb 1.5" straight spring that was impossible to install by the photos in the manual. Then dissassemble the whole thing three times to get the end play right.

JJK

Link to comment
Share on other sites

Most modern cars have speed limiters, not rev limiters. They get up to a certain speed (172km/hr/107mph with mid-'90s Chevy Luminas, 188km/hr/117mph with some Dodge products, 255km/hr/158mph with some Mercedes cars, for just a few examples) and don't go any faster. Some do it smoothly, others get kind of jumpy when they hit their limited speed.

One benefit to the car manufacturers is that they can fit tires with lower speed ratings, like S or T, which are cheaper. That really adds up when you're buying hundreds of thousands of tires to fit to the cars coming out of those factories.

Islander,

I beg to differ, most modern cars not only have speed limiters, but they also have rev limiters as well, even mini vans. I recently busted the window out of a car that a drunk driver had passed out in and slammed into the back end of another vehicle. The driver was slumped over the steering wheel passed out. I was late getting out of work from working out after my shift and I kept on hearing and engine tacking up. I thought some dumb chick was reving an engine to try to jump a dead battery. After about 3 or 4 minutes, I went to investigate and found the interior filling up with radiator smoke and hitting the rev limiter repeatedly as the thing was stuck on wide open throttle. I kicked out a window, unlocked the door, craeled across the driver and shut it off before getting help.

Roger

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...